Method of and apparatus for burning liquid fuel



P 1947- R. DE LANCEY 2,423,808

IETHODS OF AND APPARATUS FOR BURNING LIQUID FUEL Filed Feb. .6, 1941 s Sheets-Sheet 1 2 ago 2 ooo I 5 1 0 0 g 0 0 0o K o 0 I3 '27 30 v u [3a Z0 I Z7 x I! Q 3 4 24 I l 5/ 5/ 2 ,1 f; 45 Z5 4 u I! 45 i 5b \OIL 49 ,0 a r\ y J4 J6 J5 Tia-2. as 7 Tlclla.

l P1511 W522i) ATTORNEY y 1947- R. w. o: LANCEY 2. 23.808

IETHODS OF AND APPARATUS FOR BURNING LIQUID FUEL Filed Feb. 6, 1941 3 Sheets-Sheet 2.

INVENTOR RALPH W DELANCEY ATTORNEY July 8, 1947. R. w. DE LANCEY METHODS OF AND APPARATUS FOR BURN ING LIQUID FUEL Filed Feb. 6, 1941 3 Sheets-Sheet 3' R4139 n. DEM/van Aflonnm Patented July 8, 1947 mi'rnon or AND APPARATUS FOR BURNING moon) FUEL Ralph W. De Lancey, Meriden, 111., asslgnor to The Miller Company, Merlden, poration of Connecticut- Conn., a cor- Application February '6, 1941, Serial No. 377,613

cream. 1

The present invention relates to methods of and apparatus for burning liquid fuel, and is more particularly directed toward. pot type 011 burners and their method of operation.

The field of the pot or vaporizer type oil burner has heretofore been practically restricted to the burning of kerosene oil'and the more refined fuel oil such as No. 1. These oils have lower distillation points and lesscarbon residue than the less expensive and less refined fueloils (of higher heat value), such as Nos. 2, 3 and 4, and when one attempts to burn No. 2 or poorer oil'in pot type burners heretofore available the operation has been unsatisfactory. The higher or less volatile ends and carbon residues rapidly accumulate in the burner and the efficiency of the burner 'falls off rapidly until it refuses to operate.

The limitations inherent in such structures have made them unsuitable for use in the heating plants of small homes, in hot water heaters and the like, for they are too expensive to operate and require too much attention and too frequent servicing.

The present invention contemplates improvements in such burners and their operation whereby the lower grades of fuel oil may be successfully burned and the servicing and attention required is comparable to that of otherbetter type oil burners.

- Whenever such lower grade fuel oils are burned in a vaporizer or pot there tends to be an accumulation of carbon residues which are brought about by the difficulty of burning away the last bits of carbon on the comparatively cold surface where the liquid oil is held. During thehlgh fire operation it is important to reduce this carbon accumulation as much as possible, but with the lower grade fuels it is not possible to-completely avoid the formation of carbon residue after long continued high fire. As burners of this type are intended for intermittent operation it is general to employ an oil pilot during the period when high fire is not required. A similar problem' is presented by the accumulation of carbon residue during the pilot operation. The pilot flame, of course, is a very small flame and may burn for many hours before there is a demand for high fire operation. Carbon has a tendency to form rapidly around the pilot of ordinary burners due to the fact that the oil is coming in contact with a comparatively cold surface or is ona surface at a much'lower-temperature than it should be in order to vaporize the oil so that it could burn.

The present invention contemplates the provision of oil burners wherein the inevitable or 2 unavoidable accumulation of carbon residue during high fire operation is eliminated or consumed during the succeeding pilot operation, wherein the pilot is designed so as'to reduce the carbon accumulation due to pilot operation to a minimum, and wherein the alternate high and low fire operations may be made effective in removing the previous accumulation of carbon; that is to say, that when the burner goes from high fire to low fire or pilot there is a burning up of the carbon residue which accumulated during the high fire operation so that on the next high fire the burneris clean or substantially clean; also the carbon deposit which accumulates during the period the pilot is operating is later submerged in oil so as to become softened and saturated whereby it is more easily burned away during the early part of the succeeding high fire operation.

Other and further objects will hereinafter appear as the description proceeds.

The present application is a continuation in part of my p nding application Serial No. 299,943

filed October 18, 1939, for Liquid fuel burners (now Patent No. 2,290,544 of'July 21, 1942).

The accompanying drawings show; for purposes of illustrating the present invention, two of the many embodiments in which the invention may 'takeform, it being understood that the drawings are lllustrativeof the invention rather than limiting the same. I

In these drawings: Figure 1 is a vertical'sectional view through a 'form of oil burner designed to use forced draft induced by a fan directly below the oil burner pot or vaporizer;

Figure 1a is a fragmentary-sectionalyiew similar to Figure 1 showing the pilot well without oil in it;

Figure 2 is a top'plan view of parts in section on the line 2-2 of Figure l;

Figure 3 is a verticalsectional view through a furnace-with oil burner and forced draft supply, the latter being external of the furnace;

Figure 3a is a fragmentary view drawn to an enlarged scale on the same section as Figure 3;

Figure 4 is a sectional viewon line 4-4 of Figure 3;.

Figure 5 is a sectional view through the burner in the furnace and illustrating the flame propagation;

Figures 6 and6a are fragmentary views drawn to a still further enlarged scale than Flgure5;

and

Figure 7 is a sectional view an the nne 1-1 of Figure 6.

the same with I 'or other suitable support in the fire box. The

burner has an outer sheet metal casing l3, here shown as including a cylindrical member |3a and a shallow stamping l3b,,these parts being spot welded at I30, the latter being secured to the support III in a level position in any. convenient manner. A ring |4 rests on top of the casing I3 and may be held in place by screws indicated at l5, Bolts |6 extend down through the ring l4- as indicated, and support the internal parts to be described. These bolts pass through the flange ll of a casting |8 shaped to provide an annular fuel receiving trough l9 and act as a vaporizer.

- This casting'is stepped as indicated at 28, and a wardly depending fins 25.

The trough has a central opening 26 and an upper inner edge 21 which supports a central air distributor 28 preferably made of cast iron and having holes as indicated at 30, 3!, and carries an upper flame spreader 32,-

The bottom of the fuelreceiving trough l8 has an outer sloping portion 33 and an inner portion 34 of small radius so that only a. small amount of fuel is required to form an annular pool. The trough has a fuel receiving well 35 into which a coupling member or nipple 36 delivers oil. The

Q can also be removed complete and replaced when I nipple 36 passes through an opening 31' in the casing and is secured to a fitting 38 adapted to receive oil from a constant level valve, and air through a pipe 39 leading into the casing H3.

The bottom stamping |3b of the casing is provided with a comparatively large bottom opening slotted and offset, as indicated at 40, to form part of a bayonet joint connection. The stamping |3b also carries three posts 42. These posts receive springs 43 which press downwardly on a pressure plate or cup 44 whose peripheral portion 45 is curved and brought adjacent the outer part of the casing to direct the air stream up and reduce air leakage. This pressure plate has a central opening indicated at 46.

An electric motor 41 is secured to the lower face of a mounting plate 48, which has a central opening 49. The shaft 56 for the motor extends throughthis opening. and carries an impeller or blower 5|. The plate 48 has outwardly extending lugs 52 adapted to enter the opening 48 after the fashion of a bayonet joint so as to lock the plate and parts carried thereby in a place, the pressure 4 of the air will pass up by the edge of the flange ll of the trough, and this air will be forced inwardly through the openings 2| and 2|" in the cylinder 2|. Some of the air passes up into the central air distributor and through the holes 38 and 3| as indicated. The lower openings 2| and 30 will cause flame to play on the fuel surface and I vaporizing bottom sons to maintain combustion at a low leveland consume residues. The air blown out through the upper holes 2| and 3| engages the rising flame and assists in burning the fuel gases.

ever necessary.

The form of construction shown in Figures 3-7 embodie certain improvements in the construction of the parts of the liquid fuel burner in relation to flame propagation and fuel consumption, and shows an installation adapted for use as a conversion burner. v In Figure 3 a typical furnace is indicated at 68. It may be of the hot water, steam or hot air type, or any other form of furnace or heater having a combustion chamber, such as indicated at 6|. Such furnaces usually have an ash pit space 62 at th bottom. This space is here used for the reception of the body of an oil burner, and the air supply, oil supply and control are external. In this type of installation all the parts are carried by a sheet metal duct 63 extending from inside the fire box to the front of the furnace and supported in level position by three legs 64. The under face of the outer end of the duct has an opening 65 shaped like the opening 40 of Figure 1 so as to receive a motorized blower unit 66 similar to the one above described. The mounting plate 61, similar to plate 48, is held down by springs 68 carried on pins 69 secured to an apertured plate 10. This plate supports a scroll housing about the blower fan 12. r The output of the fan enters into the duct and is carried thereby into end 13 in the fire box. The upper inner end of the duct has an opening 14 adapted to receive the lower stamping 15 of a burner body. This stamping may be like stamping I31) and as the burner bodies are designed to plate acting to hold them' securely. The plate 46 has downwardly bent projections 53 to receive a cup shaped cover member 54 having an air inlet opening 55 and carrying the wiring connections 56. Various other forms of motor, fan and housing assemblies can be used.

When the parts are assembled, as shown in Figures 1 and 2, oil will be admitted through the fuel supply line and run into the trough at the rate determined by the metering valve in the fuel be used either with installations having ducts or perforated cylinder 80. with holes 8| similar to supply line. Air will be drawn in-bythe motor operated fan or blower and distributed about the periphery of the baiile plate 23 to build up a positive pressure above the battle plate, this pressure being substantially uniform throughout. Some those above described. The vaporizer is open at the center as indicated at 82 and loosely receives the lower end of a central air distributor 83 so that it can be adjusted. A baflle 84 is placed in.

the air distributor and a flame spreader 85 on top of central air distributor. The vaporizer, airdistributor and flame spreader are usually made of cast iron,

cated at ml.

The air distributor as extends out over the inher part of the oil receiving trough 80 formed in the vaporizer casting and has rows of closely spaced small holes 81, the outer row beingpreferably drilled at a slight angle to the vertical. The baille 84, having a central opening 88, impedes air movement upwardly and causes more of the air to pass down through the'holes 81 at high velocity. The air distributor 83 also carries a tube 00, preferably made of stainless steel and this tube projects down into an oil receiving well provided in the vaporizer casting. The lower end of the tube 80 carries a stainless steel washer 02 and an L-shaped stainless steel pin 88. This pin extends part way across the oil supply passage 84 which communicates with the well 8l, the oil supply pipe 95, and an air duct 96 opening into the air chest between cylinders 18 and 80.

The oil supply pipe 95 is straight and extends to a removable plug 95' so that a clean out rod may be inserted into the pilot well. The pipe 95 is also connected through suitable piping 90 with a constant level valve and metering valve indicated at 91 and forming no part of the present invention but provided with suitable controlsto provide a metered flow of fuel for both high fire and pilot operation. The pipe 85 is also connected through piping 98 extending upwardly and then downwardly into the duct 63 in front of the mouth of the scrool 1| where it is opened as shown at 98a.

While the mode of installation of the burner in the furnace will vary, the showing here is typical. The burner body is placed as shown and the intervening space closed off by a suitable hearth 99 made of refractory hearth cement. The front of the ash pit may be bricked in as indicated at Me. When the burner is operating at high fire the metering valve delivers in the neighborhood of one gallon of the #2 oil per hour (depending upon.

' as indicated at I00.

and unburned vapors pass across the bottom of the combustion chamber and rejoins the flame This air travel in the combustion chamber before the air passes to the secone or more sides; To overcome this the center air distributor and spreader may be moved slightly with a poker or piece of pipe toward the side or sides at which the flame seems to be the longest or heaviest. This will force the flame to come out of the bowl uniformly all the way around.

Inasmuch as the output of the blower is known and substantially constant it ha a known relation to the rate of oil consumption, and it is therefore possible to control accurately the total amount of air which must pass up through the chimney. The regulation of this to avoid needless excess air contributes to the economy of the installation (something impossible with gun type burners) and eliminates the unknown variable of the natural draft produced by the chimney with which the installation is used. Complete combustion and low stack temperature may therefore be had. I

In the operation of typical vaporizing burners, the light ends of the oil are more easily vaporized and burned and the heavier ends and residues tend to accumulate. The rate of accumulation of residue increases rapidly for it reduces the rate of combustion of fuel, allows the vaporizer to cool and this cycle may well continue until the accumulation is sufficient to extinguish the flame. This has generally restricted the use of mately the extent indicated. At the same time air from the blower passes up underneath the vaporizer and through the air distributor and the perforated cylinder to supply oxygen for the combustion of the oil.

At high flre a substantial amount of air is prolected downwardly at high velocity from the openings 30 or 81 so as to impinge on'the vapors immediately above the oil pool, this air spreads out over the oil and the vapors start burning. The flame is met by other jets of air coming through the lower portion of the perforated cylinder, and as the flame rises, more and-more air is supplied from the outside air chest. In operation the flame appears to eddy about as indicated at I00 in Figure 5, and it does not reach over to the outer wall of the air distributor. Un-

, burned, combustible gases may be passed from the region indicated by stippling through a tube and burned to demonstrate this. gases rise and meet the hot air passing out below the flame spreader and flame is formed as indiand cause a very eflicient mixing of the rising vapors and flame so that combustion is improved. The entire flame issues at a very flat angle as shown in the drawings and impinges on the lower portions of the walls of the combustion chamber These combustible The jets are diagonally directed such burners to the higher grades of fuel oil. The present burners have been found to operate very satisfactorily with #2, and even lower grades, of oil over long periods of high fire operation with but little accumulation of residue. Here several factors contribute to slowing up accumulation of residue. There is always a large, fiat, shallow annular pool or fllm of oil through which heat can readily penetrate and vaporize the heavier ends of the oil. There is only a peripheral edge where the oil surface meets the metal of the vaporizer so that residue which does form does not decrease the pool area appreciably. Also the jet of air from the central air distributor play on the surface; of the pool at high velocity, .whereupon ignition takes place and a very hot flame is projected across the vpool toward itsedge where the residue tends to accumulate, thereby keeping the residue very hot. It is also apparent that the air distributor and flame spreader are at high temperatures and they radiate heat into the combustion chamber of the burner assisting in keeping the vaporizer hot. The importanceof maintaining high temperatures will be appreciated when it is realized that from to 3% of the oil is not vaporizable at temperatures of 575 F. to 650 F. Obviously a burner that does not have its vaporizer at temperatures well above 650 will soon fill up with carbon formation to well remains, the hot jets playing across the vaporizer will cause the residues to ignite and be consumed so that the vaporizer is self-cleaning As the oil in the well is consumed its surface drops below the bottom of tube 90 and hot air from the air distributor now streams against the 011 surface to facilitate combustion. Air from the air chest blows through the passage 90 (or 38), and additional air intercepted by the pipe 98, opposite the blower, passes along the oil pipe 85, so that an adequate supply of air is maintained to the well. As this air passes by the bent pin 93 it is diverted and caused to spread aboutthe pilot well. The washer 92 and pin 93 are directly over the burning oil and become very hot so that heat is radiated into the well. As a result the pilot operates at a low rate (1 cc. per minute) over long periods with only a very small residue. Whatever residue is formed is submerged in oil during the succeeding high fire operation, and is softened and loosened thereby so that when the burner is again returned to pilot operation this residue is readily consumed. Tests indicate that with #2 oil continuous pilot operation may be had for periods beyond any which may be expected inburner operation.

As the usual mode of operating such burners contemplates alternate high fire and pilot, and the apparatus here described serves to consume the accumulation of one period of operation in the succeeding operation, it i possible to maintain the burner clean for very long periods. The servicing need be no more frequent than with gun type burners.

Since it is obvious that the invention may be embodied in other forms and constructions within the scope of the claims, I wish it to be understood that the particular forms shown are buta few of these forms, and various modifications and changes being possible, I do not otherwise limit myself in any way with respect thereto.

' What is claimed is:

1. The method of burning fuel oil with substantial carbonaceous residue in the annular vaporizer of a pool forming pot-type burner, which comprises maintaining oil combustion at a high rate for heating purposes and to heat the vaporizer to a high temperature and a blast of burnerheated hot air directed downwardly onto and across the pool from both sides to thereby bring about as a result of said high fire operation an accumulation of hot carbonaceous residue in the vaporizer, and thereafter supplying the oil at a lower rate to maintain a pilot flame and continu ing said air flow to supply burner heated air to the vaporizer for burning the residue.

2. The method of claim 1, characterized in that the air flow is a uniform, continuous forced draft.

3. The process of burning fuel oil with substantial, non-distillabl'e carbonaceous residue wherein such oil in a pool is vaporized and burned by heated air jets directed .down into and-transversely across the pool, the vapor immediately above the oil liquid thermally insulating the liquid are continued to supply air for combustion of the residue.

4. The method of burning fuel oil with substantial, non-distillable carbonaceous residue which comprises feeding the liquid fuel into an annular vaporizer with an upwardly and outwardly sloping bottom'so that the depth of the pool of liquid at its edge is negligible, blowing air downwardly against the deepest portion of the pool where combustion is initiated and radially across the pool surface, passing the mixed air and vapors outwardly past the hot surface of the vaporizer beyond the edge of the pool, and blowing air inwardly across the top of the vaporizer.

5. The process of burning fuel oil with substantial, non-distillable carbonaceous residue, the oil being in a pool in an annular pot below an annular combustion chamber which comprises blowing heated air downwardly into the pot from outside and above its inner edge to start combustion, concurrently blowing air inwardly across the combustion chamber to supply oxygen to the rising flame but at an insufficient velocity to burn the combustible gases adjacent the inner wall of the combustion chamber, and concurrently supplyingan outwardly directed blast of heated air at the top of the combustion chamber to facilitate combustion of said'unconsumed gases.

6. An oil burner having an annular oil receiving trough interrupted by a pilot well, anoil supply pipe to feed oil by gravity to the well where it may overflow into the trough, an outer air chest about the trough and having a perforated'cylinder to direct air inwardly above the trough, an inner air distributor above the trough and having openings at a greater radius than the inner walls of the trough to direct air jets downwardly into the inner part of the trough so as to cause flame to sweep outwardly across the trough, and

a tube carried by the air distributor and extend ing into the well to be below the level of the oil when it is deep enough to flow into the trough and adapted to conduct air into the well when the level of oil in the well recedes and be heated by the pilot light burning in the well.

'7. An oil burner such as claimed in claim 6, wherein the lower end of the tube has an enlargement to spreadthe pilot flame and be heated thereby. 1

8. An oil burner such as claimed in claim 6, having an air bleeder from the air chest into the supply pipe to supply air to the pilot flame.

9. An oil burner such as claimed inclaim 6, having an air bleeder from the air chest into the supply pipe to supply air to the pilot flame;

and wherein the lower end of the tube carries an air deflector which projects into the air from said bleeder.

10. In an oil burner, apilot well connected to an oil supply line, an air supply tube joining said oil supply line to supply air to the well in the same direction the'oil flows, a second air supply tube leading downwardly into the well, and a common source of air under pressure for both air supply tubes.

11. An oil burner such as claimed in claim 10, wherein the second air supply tube has an enlargement at the lower end to spread the pilot flame and be heated thereby and carries an air deflector which projects into the air stream from the flrst air supply tube.

12. The improvement in oil burners employing an annular vaporizer adapted to be heated when the burner is in operation and having an upwardly and outwardly sloping bottom so that the, pool depth is greatest near the axis and negligible at its edge, which improvement comprises means for directing air jets substantially vertically 9 I downwardly against the deepest portion of the pool where combustion is initiated, the air Jets being deflected radially outward across the pool surface, so that the mixed air and vapors pass upwardly past the hot surface; of the vaporizer beyond the edge of the pool, and means for blowing air inwardly across the top of the vaporizer to-intercept and mix with the outwardly moving air and vapors.

13. Oil burning apparatus comprising an annular vaporizing pot having an annular oil receiving receptacle above a predetermined level, the receptacle being of uniform contour so that the inner and outer peripheries of the pool maintained therein for high fire are circular, so that uniform high fire combustion conditions may be maintained about the entire pot, the pot having a well below said level into which the fuel recedes when the supply is insuflicient so as to maintain a pilot, a supply reservoir, slightly above the level of the receptacle fuel line, a pipe interconnecting the reservoir andthe bottom. of the well, the pipe extending horizontally from the bottom of the well for a substantial distance and being completely filled with oil when the pool is formed in the receptacle, an air chest, a blower for maintaining a pressure in the air chest above atmospheric but less than the hydrostatic pressure in the top of the pipe when thus filled with oil, and a tube leading from the air chest to the top of the oil pipe at a point spaced from the well whereby when the oil recedes below the level of the top of the pipe the liquid seal is broken and air is blown through the pipe in the direction of oil flow to supply air during pilot operation for burning fuel in the well. 1

14. The improvement in fuel oil burning means employing an annular vaporizer having an upwardly and outwardly sloping bottom so that the depth of a pool of oil thereintapers to a negligible depth at its edge, the vaporizer beingnormally heated to vaporizing temperature; and gravity means for feeding oil to the vaporizer to form a pool, which comprises means forblowing burner heated jets of air downwardly against the deepest part of the pool where combustion is initiated and causing this air to cross the pool surface and the mixed air and vapors to pass outwardly over the hot exposed surface of the vaporizer, and means for blowing additional jets of air inwardly across the vaporizer to meet the outwardly moving air and vap'ors and supply air for continuing combustion. 1

, 15. Means for burning 611 comprising an annular vaporizing pot, an annular combustion chamber above the pot, means for blowing heated air downwardly into the pot from outside and above its inner edge to start combustion, means for concurrently blowing air inwardly across the combustion chamber to supply oxygen to the rising flame but at an insufficient velocity'to burn the combustible gases adjacent the inner wall of the combustion chamber, and means for concurrently supplying a downwardly and outwardly directed blast of heated air at the top of the combustion chamber to facilitate combustion of said unconsumed gases.

16. In a pot type burner, an annular vaporizing pot, a central air distributor carried on top of the inner periphery of the pot, the central air distributor having an outer cylindrical wall of larger diameter than theinner periphery of the pot and having openings for delivering air downwardly into the pot, a flame spreader carried by and spaced from the top of the central air distributor, and a baflle supported inside the central opening smaller than the interior opening in the central air distributor to impede air movement upwardly to the flame spreader and divert air toward the first mentioned openings.

1'7. The improvement in pot type liquid fuel burners having means for supplying fuel at a rate to maintain a high fire therein and for discontinuing such rate of flow, an annular fuel receiving trough defined by a bottom wall and by annular upwardly extending inner and outer walls to holda shallow pool of liquid fuel and from which'fuel is adapted to be vaporized and burned except for residues which tend to accumulate therein, a perforated cylinder extending upwardly from the outer wall, and an outer casing having an air-tight connection with the top of the perforated cylinder and extending below the trough to form an air chest and adapted to be continuously kept under positive pressure irrespective of the supply of fuel and adapted to be heated by the combustion of fuel, which improvement comprises perforations in the cylinder close to the pool surface whereby hot air jets blown inwardly through the same mingle with vapors rising from the pool, and a central air distributor extending upwardly from the inner'wall of the trough and communicating with the airchest, the central air distributor having an enlargement close to the top of the trough and substantially opposite the lowermost perforations of the cylinder-and provided with substantially vertical openings at greater radius than the inner wall of the trough and opening at a distance above the bottom of the trough and such that air jets are directed downwardly against the innermost'part of the trough so as to mingle with the vapors and cause flame to'sweep outwardly across the surface of the pool of fuel and toward the periphery of the trough to meet the jets of air entering through the lowermost perforations of the cylinder, the continuously produced air jets issuing from the central air distributor and cylinder maintaining'combustion of the fuel while the surface of the oil in the pool is receding and burning the residues. I

18. The improvement in pot burners such as claimed in claim 1'7, having a downwardly and outwardly flaring flame spreader carried by the central air distributor opposite the top of the perforated cylinder and directing air from the cen-v tral air distributor downwardly and outwardly.

19. The improvement in oil burners employing an annular vaporizer adapted to be heated when the burner is in operation and having an upwardly and outwardly sloping bottom so that the pool depth is greatest near the axis and negligible at its edge, which improvement comprises means for directing air jets substantially vertically downwardly against the deepest portion of the pool where combustion is initiated, the air jets being deflected radially outward across the pool surface, so that the mixed air and vapors pass upwardly past the hot surface of the vaporizer beyond the edge of the pool, means for blowing air inwardly across the top of the vaporizer to intercept and mixwith the outwardly moving air and vapors, and means above the downwardly directed jets 'for blowing air outwardly into the ascending burning gases.

20. Means for' burning oil comprising an annular vaporizing pot, an annular combustion chamber above the pot, means for blowing heated air downwardly into the pot from outside and above concurrently blowing air inwardly across the combustion chamber to supply oxygen to the rising flame but at an insufiicient velocity to burn the combustible "gases adjacent the inner wall of the combustion chamber, and means for concurrently supplying an outwardly directed blast of heated air at the top of the combustion chamber to facilitate combustion of said unconsumed gases.

2 1. The method of burning fuel oil with substantial carbonaceous residue in the annular vaporizer of a pot-type burner, which comprises maintaining oil flow at a high rate to maintain a pool in the vaporizer while concurrently maintaining combustion at a high rate for heating purposes andto heat the vaporizer to a high temperatureand also maintaining a blast of burnerheated hot air directed downwardly onto and across the pool from both sides to thereby bring about as a result of said high fire operation .an accumulation of hot carbonaceous residue in the vaporizer, and thereafter supplying the oil at a rate insumcient to maintain the pool at high fire level so that its level ebbs to a substantially reduced amount, and continuing said air flow to supply burner heated air to the vaporizer surfaces exposed thereby and burning the residue of! said vaporizer surfaces.

RALPH W. DE LANCEY.

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